In this paper, a novel compact tri-band monopole antenna for WLAN/WiMAX applications is proposed. By using a horizontal H-shaped strip and an L-shaped open end stub, and a deformation inverted T-shaped strip through a matching line attached to the 50-Ω feed-line, tri-band has impedance bandwidths for S₁₁≤ -10 dB are 2.4-2.7 GHz, 3.4-3.72 GHz, 5.06-5.85 GHz, covering 2.4/5.2/5/5.8 GHz for WLAN and 2.5/3.5/5.5 for WiMAX applications can be acquired. Experimental results show that the proposed tri-band antenna has nearly omnidirectional radiation characteristics across all the operation bands. Furthermore, the antenna with compact size of 30 × 20 × 0.8 mm³ has simple structures.

In present paper, the effect of relativistic hot electron beam for field aligned Whistler mode waves has been studied theoretically in the presence of AC electric field perpendicular to magnetic field. Studies have been performed using perturbative approach along with the method of characteristic solutions and are valid for comparatively small ambient magnetic field of Uranus, of the order of nano Tesla, as observed by Voyager 2. The detailed derivation and calculations has been done for dispersion relation and growth rate for magnetosphere of Uranus. Analyses are done by changing various plasma parameters which are explained in result and discussions section of this paper. Extensive study of wave-particle interactions and numerical calculations concludes that in case of injection of a distribution of particles having a positive slope in v_⊥, temperature anisotropy remains the main source of free energy. It is seen that other effective parameters for the growth of whistler mode waves are AC frequency and higher number density of hot electrons. We also learn that even the minimal presence of such energetic particles having a positive slope of distribution function and increasing power of perpendicular thermal velocity can increase the growth rate significantly in the magnetosphere of Uranus. The present work is basically based upon the theoretical investigation and mathematical analysis of the magnetosphere of Uranus, supported by satellite data.

Based on energy injection and free resonant mode, an approach to optimize the startup frequency setting of the voltage-fed inductive power transfer (IPT) system is proposed to mitigate the effects of uncertain system parameters and load conditions. Differential equations of the primary resonant network on the free resonant mode is firstly established, then the free resonant frequency with different parameters and load conditions is calculated and verified with the soft-switching frequency of system based on stroboscopic mapping modeling method and fixed points theory. By controlling the micro-energy injection of system and free resonance, the frequency of free resonant mode is detected, and is regarded as the fixed frequency of startup process. Hence, the proposed strategy solves the uncertainty of the startup frequency and system re-setting to fit with changed system parameters and load conditions. This method also initiates immediate protection when the system operates under zero loads. In sum, our experimental results verify the theoretical implication, effectiveness, and merits of the proposed approach.

This paper proposes a novel design methodology for dual-band Doherty power amplifier (DPA) with simplified offset-lines. The methodology is validated with the design and fabrication of a 10 W GaN based DPA for Global System for Mobile Communications (GSM) and Wideband Code Division Multiple Access (WCDMA) applications at 0.90 GHz and 2.14 GHz, respectively. In the measurement results, the DPA achieves a drain efficiency (DE) of 51.2% with an output power of 37.2 dBm at the 6.5 dB output power back-off (OBO) from the saturated output power at 0.90 GHz, and a DE of 39.9% with an output power of 37.4 dBm at the 6.5 dB OBO at 2.14 GHz. Linearity results using 20 MHz 16QAM signal show an adjacent channel leakage ratio (ACLR) of -48 dBc and -43 dBc with the average output power of 37.2 dBm and 37 dBm at 0.90 GHz and 2.14 GHz, respectively.

This paper introduces a new numerical method to calculate the group delay, chromatic dispersion and dispersion slope of weakly-guiding optical fibers with arbitrary radial refractive index profiles. It is based on the analytic differentiation of the propagation coefficient up to the third order. The simulation results are compared to experimental data, with those calculated by other approaches and exact data where possible. Due to the analytical differentiation of the matrix equation, the method is more accurate compared to other approaches, it is also much faster than numerical differentiation as allows avoiding repeated solution of the eigenvalue problem to calculate the derivatives of the propagation coefficient. The precision of the method is limited only by the approximation errors of the mode solver. The Galerkin method with Laguerre-Gauss basis functions is used to determine the propagation coefficients of weakly-guiding structures. The new method enables fiber manufacturers to rapidly design dispersion characteristics of graded index, step index, single- and multiple-clad fibers, as well as few-mode and bend insensitive fibers.

Permanent-magnetmotorsare widely usedin-wheel motors of electric vehiclesand hybrid vehicles. Based on a movable stator design, this paper presents a new type permanent-magnet motor, whose torque can be adjusted in order to meetdifferent driving requirements. The stator geometryis varied by means of changing movable stator positions.Accordingly, the air-gap lengthin permanent-magnet motorsis changed so that torque can be adjusted. To derive an analytical model, Fourier series expansions are employed to formulate air-gap geometry variation. The analytical modelis validated by finite element numerical results.Concerning motor torque variation capability achieved in this study, the ratio of the largest vs. the smallest torque is 2.3.

Partial Discharge (PD) measurements may be affected by external noise and disturbances of various natures such as interference from broadcasting stations, stochastic noise, pulses from power electronics, etc. Extracting PD pulses from such a noisy environment is therefore a crucial issue. This paper presents a wavelet based technique for automatic noise rejection. The core of the paper is the use of an improved methodological approach for the selection of a suitable wavelet, which aims at summing up the benefits and overcoming some limitations of previous techniques. Firstly, a very wide set of training signals is used for the identification of the decomposition level and for the calculation of suitable performance parameters that identify each wavelet; then a Performance Fingerprint is introduced in order to summarize the ability of a specific wavelet to reconstruct a partial discharge waveform, and a distance criterion is used for the selection of the most suitable wavelet. Afterwards, useful information is collected for the reconstruction of the PD signal, and finally, results on the application of the algorithm for a set of numerical and experimental signals are presented.

A broadband power amplifier designed and implemented in Doherty configuration is illustrated in this paper. Both input and output networks adopt the broadband matching topology. Additionally a compensation network, consisting of a series transmission line shunted with a capacitance, is set behind the peak amplifier to avoid in-band power leakage in the low-power section while at the cost of peak output power in partial band. A novel coupler is designed as an uneven power-divided splitter and experimentally validated for a broadband power amplifier module. A tradeoff of bandwidth, efficiency and output power is fulfilled through parameters select and postproduction tuning. According to the measured results, the proposed broadband Doherty power amplifier achieves an average saturated output power of 42 dBm, an average gain of 10.6 dB, an average peak and 6 dB back-off efficiency of 48.4% and 32.8%, respectively, and a fractional bandwidth of 51.4%, from 1.3 GHz to 2.2 GHz. The adjacent channel power ratio is better than -40 dBc when the amplifier is driven with 10-MHz QPSK signal, thus exhibiting a high linearity performance.

Dipole antennas on a substrate without a ground plane are common in wireless sensor networks and RFID applications. This paper reviews a number of theoretical approaches to solving for the effective permittivity when the substrate material is thin. The surface impedance and slab waveguide propagation techniques are compared to a capacitive solution and an insulated wire antenna. The insulated wire method gives most accurate results (< 3.5%) and was verified using numerical modeling and experimental work. Measurements on a planar straight dipole on FR4 (f_c = 1.50 GHz) compare favorably with the antenna modelled without the substrate and scaled using the insulated wire technique at (f_c = 1.49 GHz). The method can be readily incorporate the effect of an RFID antenna on a thin plastic film placed on a wide variety of lossy and lossless objects.

In order to improve the reconstruction accuracy of near-field SAIR, a novel regularization imaging algorithm based on an accurate G matrix is proposed in this paper. Due to the fact that the regularization reconstruction is usually an underdetermined problem, inaccurate operation matrix G will lead to great reconstruction error in the imaging results, or even the normal imaging cannot be obtained. In this paper, we establish an accurate G matrix based on the accurate imaging model of near-field SAIR. Compared with the traditional G matrix with some unnecessary approximations, the proposed G matrix without approximation can improve the reconstruction accuracy effectively. For improving the accuracy of matrix G further, the corresponding parameters are corrected according to the RMSE between the imaging results of the regularization method and modified FFT method which is not sensitive to the parameters' change. The effectiveness of this calibration method has been tested by 1D simulation experiments. Moreover, the 2D simulation experiments demonstrate that the proposed accurate G matrix can improve the imaging accuracy of regularization method effectively. Finally, the 1D imaging experiment is performed to test the effectiveness of the proposed method for the actual synthetic aperture imaging further.

Broadside coupling mechanism between different patch resonators is deployed for designing power dividers to provide bandpassing effect. To demonstrate, two sector-shaped patches are combined and concentrically stacked on top of a circular microstrip resonator where pairs of concentric arc-shaped slots and radial notches are etched to perturb the current distribution so that an additional pole can be obtained to broaden the operational bandwidth. The use of circular patch enables the expansion of output ports without increasing the design complexity. Also, it was found that broadside coupling generates transmission zeros which can be used to sharpen the rolloff skirt for a better selectivity. In this paper, the corresponding design theory and methodology are elucidated, together with the detailed parametric analysis.

A broadband circularly polarized (CP) slot antenna array fed by an asymmetric coplanar waveguide (CPW) with stepped and inverted T-shaped strips is proposed. Using four square slot antenna elements with sequential rotation oblique feed and a modified sequential-phase (SP) feeding network, broadband CP can be achieved. The measured -10 dB reflection coefficient bandwidth and 3 dB axial ratio (AR) bandwidth are 55.4% (1.63-2.88 GHz) and 58% (1.65-3 GHz), respectively. Good radiation characteristics with gain more than 6 dBic over the operating band are obtained by the proposed antenna array with a compact size of 155×155×0.8 mm³. Details of the proposed antenna array design and experimental results are presented and discussed.

The pattern synthesis for large antenna arrays has drawn significant attention because of its wide applications.This paper introduces a hybrid approach for the fast pencil beam pattern synthesis of the large non-uniform linear or planar array, which can significantly reduce the computational cost, the number of antenna in the array, the minimum sidelobe level and the null control.The proposed method has an iterative scheme which is composed of the nonuniform Fourier transform (NUFFT) and the global optimization method to minimize the peak sidelobe level and control the null. The NUFFT is utilized to determine excitation magnitudes for a fixed positions non-uniform array. The global optimization is used tofind the optimal postions lead thepeak sidelobe level minimum alternatively.The lower excitations can be deleted due to yielding less performance on sidelobe level, which is calledthe array removal strategy.Compare with conventional methods,the simulations on synthetic models show thata minimum sidelobe level and null control can be obtained in processing sparse linear and concentric circular antenna arrays more efficiently.

A Planar elliptic broadband antenna with reconfigurable dual stop-bands performance was successfully designed and performedfor multi-standard wireless communication systems. The proposed antenna consists of a broadband micro-strip fed printed monopole operating in the frequency range 0.75-6 GHz. The notch-band characteristic was obtained by printing two Open Loop Resonators (OLRs) on the front side of the substrate close to the micro-strip feed-line. By adjusting the OLRs parameters, mono or dual band-rejection can be obtained. The passive broadband antenna was optimized to achieve narrow band rejection over the UMTS-band (around 2.1 GHz) and the WiMAX-band (around 3.5 GHz). The agility was produced by loading a varactor diode on each OLR. The major advantages of this structure are the high selectivity of the dismissed-bands, continuous reconfiguration and wide tuning range of the notched bands. Four prototypes were realized and experimentally characterized. The measured tuning rangescorresponding to the notched bands are about 850 MHz (2.25-3.1 GHz) for the rejected UMTS-bandand 570 MHz (3.84-4.41 GHz) for the WiMAX-band. Simulated and measured resultsare presented and discussed.

A compact UWB bowtie-slot antenna (36×23 cm²) fed by a CPW transition is proposed for an improved ground-coupling radar. The antenna has an operating frequency band in the range [0.46 ; 4] GHz. Full-wave modeling using the FDTD approach has allowed to study in details the antenna radiation characteristics in air and in the presence of a soil. Afterwards, a radar system made of a pair of independent shielded bowtie antennas has been considered to probe the sub-surface very close to the air-soil interface. The polarization diversity in the E and H-planes is an important aspect which has been studied in order to further detect the orientation of damages (cracks, delaminations…) in civil engineering structures. Measurements in a dry and wet sand in different system configurations have allowed to first characterize the GPR system and to draw comparisons with numerical results. The ability of the radar to detect small buried objects is investigated.

In this paper, the finite element method (FEM) is applied to the analysis of three-dimensional (3D) electromagnetic structures. The incomplete Cholesky (IC) preconditioner based on shifted operators is used to solve the finite element linear systems. Several strategies are adopted to raise the efficiency and robustness of the preconditioner. Numerical experiments for several microwave devices demonstrate the superior numerical convergence and robustness of the proposed preocnditioner.

A triple-band bow-tie-shaped CPW-fed slot antenna design for wireless communication applications is proposed. The antenna consists of a signal strip, two conducting strips and bow-tie-shaped slots. With simple tuning geometrical parameters, the proposed antenna is suitable for WLAN 2.4/5.2/5.8 GHz bands. This antenna is designed on a single-layer PCB FR4 substrate with permittivity ε_r = 4.4, loss tangent tanδ = 0.0245 and thickness h = 1.6 mm. The antenna size of the radiating area and ground plane is 60×45 mm². The measured results show a positive agreement with the simulated results.

An efficient optimization technique for frequency selective surface (FSS) radome with nonuniform wall thickness is proposed to improve the power transmission efficiency and the boresight error (BSE) of FSS radome simultaneously. The high-frequency method based on the approximate locally planar technique is used to evaluate the transmission performance of FSS radome. An efficient multi-dimensional adaptive sampling method combined with spectral domain method of moment (MoM) is employed to analyze transmission performance of FSS structure. The immune clone algorithm (ICA) is applied to the design of a FSS radome, in which the linear combination of the maximizing power transmission efficiency and the minimizing BSE is adopted as the affinity function, and the radome wall thickness is optimized. A design example for the three-dimensional tangent ogive radome with nonuniform thickness is given. The results show that the power transmission efficiency is improved significantly and the BSE of the optimal antenna-radome system is also reduced over the antenna scan volume.

An accurate complexity-reduced simplified Volterra (ACR-SV) series is introduced for RF power amplifiers (PAs). Based on the conventional simplified Volterra (SV) series, it takes memoryless nonlinearity and memory effect into consideration separately, while connected with a nonlinear memory effect (NME) in order to increase accuracy of the model. The proposed ACR-SV model is assessed using a GaN Class-F PA driven by two modulated signals (a WCDMA 1001 signal and a single carrier 16QAM signal with 40 MHz band width). The experimental results in forward modeling and DPD application demonstrate that the proposed ACR-SV model outperforms the memory polynomial (MP) model, the augmented complexity-reduced generalized memory polynomial (ACR-GMP), and the SV model. Compared with the MP model, the ACR-SV model shows a normalized mean square error (NMSE) improvement of 2.61 dB in forward modeling, average adjacent channel power ratio (ACPR) improvement of 3.7/4.2 dB in the DPD application with less 13% number of model coefficients. In comparison with the ACR-GMP model, the ACR-SV model shows NMSE improvement of 1.39 dB, ACPR improvement of 0.7/0.6 dB with comparable number of model coefficients. In contrast with the SV model, the ACR-SV model achieves similar model accuracy, but reduces approximately 53% of coefficients.

In this paper, a novel dual notch bands Ultra Wide-Band (UWB) antenna for WLAN and WiMAX applications is presented. The antenna contains a taper rectangular monopole antenna with new feed line which is designed and modified for 2-12 GHz. To achieve notch band at WLAN frequencies, different methods are compared, such as L-shape slots for one notch or dual rings in notch designing. On the other hand, the novel F-shape feed line is designed to achieve dual notch band characteristic. The effects of stubs parameters at notch frequencies are presented. The benefit of this novel feed line is designing multi-band and reconfigurable antenna by changing stub line parameters. The simulated results of prototype antenna are obtained with HFSS and CST. Total size of the antenna is 60 mm×60 mm×1.6 mm. It is fabricated on FR-4 low cost substrate and fed by 50 Ω microstrip line.